Plug attachment for electric cords



Feb. 17, 1948. J, MEHRTENS 2,436,221

PLUG ATTACHMENT FOR ELECTRIC CORDS' Filed Feb. 23, 1944 3nventorz- Patented Feb 17,1948

UNITED STATES PATENT OFFICE PLUG ATTACHMENT FOB ELECTRIC corms John a. mama's, San Francisco, Calif.

Application February 23, 1944, Serial No. 523,803

1 Claim. 1

My invention is an improvement in plug attachments for electric cords or insulated flexible wire conductors used especially for connecting electric appliances--such as smoothing irons, vacuum cleaners, etc.with the source of electric supply, and has particular reference to that type of plug employed for connecting the cord to the outlet box.

The important object in view is to provide a plug of this type which will serve in an effective manner as a protection against the cord catching fire from the wires passing through the same, or damage to the appliance should the current capacity of the latter be exceeded, by disrupting the circuit at the plug under certain conditions without interrupting that part of the circuit from the source of electric supply which includes the terminals of the outlet box; to thereby not only afford the protection mentioned but also facilitate both the location of the trouble and reestablishment of the circuit through the cord and appliance.

My improved construction of attachment plug also contemplates a particular construction of the insulated casing thereof-which encloses the electric connections-by providing said casing with a removable portion to expose the terminal screws to which the wires of the electric cord are attached without disturbing any other part of the casing or electric connections enclosed therein.

With these principal objects in view my in vention comprises a plug having a recess in one side thereof to receivean ordinary type of ruse plug, preferably a Fusestat, in association with the usual contact blades adapted to cooperate with an outlet box, and terminal screws to which the wires of the electric cord are attached; one of the blades being directly connected to a terminal screw while the companion blade is electrically connected to the other terminal through the medium of the fuse plug-as hereinafter fully described and more specifically set forth in the appended claim.

-In the drawings:

Figure 1 is a side elevation of the plug, con structed in accordance with my invention.

Fig. 2 is a similar view, a removable part of the casing of the plug being detached to expose the terminal screws.

Fig. 3 is a detail view of the removable part of the casing.

Fig" 4 is a side elevation at right angles to Figs. 1 and 2.

H8. 5 is a plan view of thatsection of the plug 2 casing in which the electric connections are mounted, the fuse plug being shown in association therewith.

Fig. 6 is a detail view of the electric conducting element used in connection with the fuse plug, and

Fig. 7 is a detail view of a conventional type of fuse plug to illustrate an example of this element of construction of my improved attachment plug.

In carrying out my invention the casing or body of the plug-ordinarily made in two sections of insulating material--is in this instance made of three parts or sections; that is, a half section iii, in which the electric connections hereinafter described are mounted, and two cover sections i i and i2. The cover section I2 is of such size as to only cover and permit access to the terminal screws at this end of the plug, and the several sections of the casing are connected together by screws-the sections i0 and H preferably by two screws, l3, l4, while the smaller section I2 requires but a single screw, i5, for attaching it to section iii.

In one side of the connected sections of the attachment plug there is a recess i6 threaded as indicated in Fig. 5 to receive a fuse plug ll of a conventional design or constructionas for instance a Buss Fusestat-it being understood that the threaded portion of the recess in section II) of the casing registers with the threaded portion of the recess in the companion section II. The recess for the fuse plug may be formed in any convenient part of the casing, the location shown in the drawings being merely the preferred arrangement.

The attachment plug is provided with the usual contact blades IE, IQ, for making contact with the outlet box (not shown), but of any ordinary type,

and with terminal screws 20, 2! to which the wires of the electric cord 22 are connected. In this instance, however, one of the blades, i8, extends longitudinally through the attachment plug from terminal screw 20 to and beyond the other end 01' said plug, while the inner end of the cornpanion blade, l9, terminates in a cavity 23 located at the inner end of the recess in which the fuse plug is seated, and in order that the resilient inner end of said blade may move towards the inner end of the fuse plug or conductor 24 thereof-to insure contact therewith-the cavity is extended for a short distance as shown in Fig. 5. The conducting element 24 establishes electric connection between this blade and the fuse plug, and the latter is electrically connected to the terminal screw 2i through the medium or) oi metal collar 21? at the outer end of recess iii in which the fuse plug is seated, said collar heing provided with a projecting member 28 apertured at its outer end toreceive the terminal screw.

As will be obvious the wires of the electric cord are connected to the terminal screws located at and of the attachment plug opposite the from which the contact blades project, and

that the casing is provided with a cavity, 2%, to

accommodate these connections, as well as with an opening through which the cord passes. Therefore, as hereinbefore explained, this end of the attachment plug is enclosed by the removable cover it to facilitate connecting the wires of the electric cord to the terminal screws, and as the other electric elements contained within the casing of the attachment plug-s-with the exception of the fuse plug are permanent elements of the attachment plug, and need not be disturbed, the cover section ii may be more securely attached to section 50 than by screws.

It will be obvious from the foregoing description, in connection with the accompanying drawings, that in use when the current in the circuit which includes the attachment plug, electric cord and appliance exceeds the capacity of any one of these devices it will "blow the fuse, and as the latter is located at the outlet box the current will be cut ofi at this point, or open the circuit here, to thereby protect the electric cord and appliance from damage that might otherwise occur. Of course the amperage capacity of the fuse will be governed by the current capacity of the cord and appliance to which it is connected; consequently in the event of failure in the operation of the electric appliance the troublei:f clue to the blowing of the fuse-can be quickly located and the circuit readily reestablished by simply renewing the fuse plug or Fusestat. Furthermore, as any one of the numerous commercial fuses may be used in connection with my improved attachment plug the repair can be readily made by an unskilled or inexperienced person. However, in order to limit the amperage passing through the attachment plug to the elec tric cord and appliance used in connection therewith-and thereby provide additional protection in the use of the cord and appliance-I contourplate making the threaded recess in the attachment plug of such size and pitch of thread as to receive a Fusestat of a definite amperage according to the prospective use of the cord.

In the practise of my invention the particular construction disclosed herein may be modified in some respects-within the spirit and scope or my invention-as for instance the sections iii and ii of the casing of the attachment plug instead of being connected by screws, and there: fore separable, could be permanently connected in any suitable manner leaving onlythe section 52 removable, for connecting the wires of the electric cord to the terminal screws, and other minor changes that may be suggested in the manufacture of the device.

I claim:

A plug attachment for an electric cord comprising, a casing section having a semi-cylindrical recess in-one face thereof, a second casing section of shorter length than the first casing section and having a semi=cylindrical recess in one face thereof, means detachably holding said casing sections together with said recesses in register to provide a substantially cylindrical shaped re== cess open at one side of the plug for receiving a fuse plug therein, a contact blade projecting from one end or the plug and extending along a groove in the casing sections to the other end of'thc plug and beyond the end oi the second casing section, a second contact blade projecting from said one end of the plug in grooves in said casing sections and terminating adjacent the inner end of said cylindrical recess, said casing sections having a cavity therein permitting resilient move ment of the second contact blade, a conductor extending from said cylindrical recess beyond the end of the second casing section, means for attaching an electric cord to the first contact blade and said conductor beyond the end of the second casing section, and a third casing section adapted to fit the first casing section and cover said cord end.

JOHN E. MEHRTENS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 18,193 Kollath Sept. 15, 1931 1,395,108 Haywood Oct. 25, 1921 1,876,823 Adams Sept. 13, 1932 1,950,181 Kelley et a1 Mar. 6, 1934 1,974,700 Adams Sept. 25, 1934 2,084,222 Senor et a1. June 15, 1934 2,214,560 Levey Sept. 10, 1940 

